This disclosure relates generally to measurements performed optically in subterranean wells and, in an example described below, more particularly provides for downhole flow measurements with optical distributed vibration/acoustic sensing systems.
It can be beneficial to be able to determine where particular substances flowed in a wellbore are located, or what substances are positioned at particular locations. For example, in a cementing operation, it is important to be able to verify that cement has been appropriately placed in an annulus between a casing or liner and a wellbore, or between tubulars.
Therefore, it will be appreciated that improvements are continually needed in the arts of determining where particular substances flowed in a wellbore are located, and determining what substances are positioned at particular locations. Such improvements can be useful in operations other than cementing operations, and in determining locations of substances other than cement (such as, gels, spacers, drilling mud, completion fluids, produced or injected fluids, etc.).